Combined typewriting and comput



April 27, 1937. H. L. PITMAN COMBINED TYPEWRITING AND COMPUTING MACHINE 5 sheets-sheet 1 Filed March 25 INVENTOR: gm @5% ATTO EY.

lll/lill!! A pril 27, 1937@ H. n.. PWMAN COMBINED TYPEWRITING AND COMPUTING MACHINE Filed March 25, 1932 5 Sheets-Sheet 2 April 27, 1937. H. L. PITMAN COMBINED TYPEWRTING AND COMPUTING MACHINE 1952 5 Sheets-Sheet 3 Filed March 25 5 Sheets-Sheet 4 H1. L. PHTMAN COMBINED TYPEWRITING AND COMPUTING MACHINE Filed March 25, 1932 April 27, 1937.

April 27, 1937. H. L. PITMAN COMBINED TYPEWRITING AND COMPUTING MACHINE 5 Sheets-Sheet 5 Filed March 25, 1952 FIGJZ, n 4

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Patented Apr. 27, 1937 UNITED STATES COMBINED TYPEWBITING AND COIMPUT- ING MACHINE Henry L. Pitman, Westfield, N. J., assignor, by

mesne assignments,

to Underwood Elliott Fisher Company, New York, N. Y., a corporation of Delaware Application March 25, 1932, Serial No. 601,173

38 Claims.

This invention relates to computing mechanism in which computing wheels rotate in one direction for addition and in the opposite direction for subtraction, and also relates to a novel tens-carrying mechanism and novel means for preventing overthrow of the computing wheels. The invention is particularly applicable for modifying the well-known Underwood-Hanson computing machine for direct subtraction, thus greatly simplifying said machine, and for simplifying the tenscarrying mechanism and overthrow-preventing mechanism of said machine.

The Underwood-Hanson machine is described in the patent to O. Minton No. 1,280,065 dated September 24, 1918, which also discloses the Underwood subtraction mechanism, whereby subtraction is effected by adding the usual complement of the subtrahend.

Tens-carrying mechanism of the Underwood- Hanson machine is described in Patent No. 1,278,812 to H. Hanson, dated September 10, 1918.

n According to the present invention, the subtraction-mechanism is much simplified in comparison with the Underwood subtraction mechanism described in the aforementioned patent to Minton No. 1,280,065. State-determining means are provided whereby the dial-wheels are caused to rotate in one direction for addition or to rotate reversely for subtraction. The subtraction is therefore direct, as distinguished from subtraction effected by adding the complement of the subtrahend.

In the present invention, the register-bars having the computing wheel driving racks and the index-pins are retained. For addition the computing Wheels are driven directly by said driving racks, whereas for subtraction the computing Wheels are driven by intermediate rotation-reversing pinions or racks which may be permanently in mesh with the driving racks. The computing wheels are normally disengaged from both the driving racks and the intermediate pinions, and by the state-determining means are brought into mesh, either with the driving racks on the register-bars or with the intermediate pinions, during an initial portion of the advance movement of the general operator, depending on the setting of the state-determining means. Said state-determining means may be normally set or conditioned for addition so that normally the computing wheels will be directly driven by the driving racks on the register-bars. For subtraction said state-determining means may be conditioned as by the operation of a subtractionkey to bring the computing wheels into engagement with the intermediate pinions.

The computing wheels remain in mesh throughout the rest of the advance movement of the general-operator cross-bar. Driving means for said general-operator cross-bar may be so arranged that at the end of said advance movement said general-operator cross-bar stands stationary for an interval of time to insure completion of the tens-carrying operation, as will hereinafter be made clear, the return movement of the general-operator cross-bar being commenced at the end of said interval. In the initial portion of said return movement, the computing wheels are caused to be disengaged before the generaloperator cross-bar picks up the advanced register-bars to restore them to their normal positions. By thus disengaging the computing wheels, before the return of the register-bars, the necessity for providing one-way connections of the computing wheels to lthe register-bars is avoided, with consequent simplification of th mechanism.

The carrying of tens from one computing wheel to another computing wheel of the next higher denomination involves the release of a springpressed normally latched register-bar stop through the movement of said first computing wheel past its carrying position. The registerbar stop in its normal unreleased position is effective to limit the movement of the registerbar for the computing wheel of next higher denomination, to the end that said register-bar may not be overthrown while being driven forward by the general-operator cross-bar. When said register-bar stop is released from its latch, and is, in consequence, caused to be withdrawn by its spring, the register-bar is permitted to advance an extra unit space to thereby carry over a tens value, said stop being still effective, however, to prevent overthrow of the registerbar, since it is only withdrawn enough to permit said extra advance.

If a register-bar stop be released and Withdrawn before the general operator reaches the end of its advance movement, the register-bar which said stop controls is, according to an important feature of the invention, advanced positively for carrying, by the movement of the general-operator cross-bar as it completes its advance stroke. To this end, the general-operator cross-bar does not enga-ge the index-pins directly for advancing the register-bars, but there are interposed ahead of said cross-bar for engaging the index-pins, the ends of a series of levers of the rst order pivoted on a fulcrum-rod carried by the general-operator cross-bar. The other and normally free ends of said levers are, in the direction of cross-bar movement, opposite the free ends of a series of similar levers of the iirst order pivoted on a iixed fulcrumrod, the other ends of said latter levers being connected to the aforesaid register-bar stops. The levers connected to said stops are capable of two positions, depending on whether or not the stop is withdrawn for carrying. Ii' a stop is not Withdrawn for carrying, the free end of the lever connected thereto Just meets the free end of the opposite lever on the fully-advanced general-operator cross-bar. The two levers thus meeting form a pincer-like arrangement wherein the index-pin is held between the register-bar stop and the opposite end of the lever on said cross-bar, said cross-bar backing up said opposite lever end. Thus the advanced position of the register-bar is secured against overthrow and also against rebound. Should a register-bar stop be withdrawn before the general-operator cross-bar reaches the end of its advance movement, the free end of the lever connected to said register-bar stop will be moved toward the free end of the opposite lever on the approaching cross-bar and thus constitutes an interponent which will engage and arrest said free end of the cross-bar lever Just before the cross-bar completes its advance movement.

It will be understood now that as said crossbar advance movement is completed, the lever on the cross-bar will be rocked because of the arrest of its free end, thereby causing an extra tenscarrying advance of the register-bar, the extra advance being positive due to the positively driven cross-bar. The levers may be so proportioned that when a suillcient extent of carrying advance is reached, the index-pin is again held between the register-bar stop and the opposite end of the lever on the cross-bar to prevent overthrow or rebound of the register-bar. The free ends of the two series of levers may be proportioned and arranged so that the levers connected to the register-bar stops may lock the levers on the cross-bar against reverse movement at the end of a carrying movement of said cross-bar levers. Such proportioning and arrangement of said free ends are also effective to stabilize the levers connected to the register-bar stops as their free interponent ends co-operate to rock the cross-bar levers, inasmuch as the lines of reaction, which the free ends of said stop-levers afford to rock the cross-bar levers and lock the same against reverse rotation, may in either case pass through the fulcrum center of said stop-levers.

If, as may happen in some computations, a register-bar stop be released and withdrawn for carrying a tens value after the general-operator cross-bar has completed its advance movement, the carrying advance of the register-bar controlled by said stop may be eilected by power derived from suitable springs connected either to the register-bar stop or its lever. In this case it will be understood that the free ends of the stoplever and the opposite cross-bar lever just meet as the cross-bar completes its advance and that a subsequent release and withdrawal of the stop will cause the lever connected therewith to be rocked by the power of the aforesaid spring, with a consequent rocking of the lever on the crossbar and a consequent carrying advance of the register-bar whose set index-pin is held between the register-bar stop and cross-bar lever as aforesaid.

It will be seen now that the cross-bar levers, broadly considered, constitute rack-engaging fingers, which, in respect to said cross-bar or any other suitable movable member on which they may be mounted, may be advanced one unitspace, thus enabling said cross-bar or movable member which has a fixed extent of movement to advance the racks an extra unit-space for carrying. It will also be seen that the advance of said fingers in respect 'to the cross-bar, and hence the carrying of the register-bars, are in most cases accomplished positively.

In practicing the invention the register-bar stops may be in the form of elongate bars connected at one of their ends to their respective levers, said ends also forming the stop or abutment between which and the cross-bar lever or finger, the index-pin is held at the end of the register-bar movement. Said stop-bars, viewed sidewise of the register-bars, may extend substantially parallel to the latter and may be latched at their other ends over a latching bar. Each computing wheel may have the usual crl'ylnl tooth. Said tooth, in the preferred form of the invention, does not, for carrying" as aforesaid, release the corresponding register-bar stop by direct engagement, but instead, for convenience of arrangement of the parts, releases said stop through an intermediate carrying lever. one end of which may be engaged by said carrying tooth, and the other end of which may engage the stop to displace the same from the latching bar. The tooth-actuated carrying levers may be mounted in the aforesaid frame, in which the computing wheels are mounted, and may be so arranged that the ends which engage the stops may properly engage said ends irrespective of the shifting of said frame either toward the register-bar racks or toward the intermediate racks.

'I'his application is in part a continuation of my co-pending application Serial No. 324.353. led December 7, 1928 (now Patent No. 1,927,951, dated September 26, 1933).

Other features and advantages will hereinafter appear.

In the accompanying drawings,

Figure 1 is a cross-section through the combined typewriting and computing machine, showing, in side elevation, details of the novel carrying mechanism.

Figure 2 is a side elevation, showing details vof one form of power-drive for the computing mechanism.

Figure 3 is a detail view, showing the construction of means whereby a universal bar for restoring the carrying stops is operated.

Figure 4 is a top plan view, looking down on the computing mechanism, to show the arrangement of four registers, and the operating parts for said registers.

Figure 5 is a skeleton view, showing, in perspective, the arrangement of said four registers, and the arrangement of a register-bar, relatively to the novel carrying means, and also bringing out other details of construction.

Figure 6 is a skeleton view, showing, in perspective, the fixed plates within which a registerwheel frame is shifted, and also showing, in detail, means for ensuring relatching of carrying stops.

Figure 'l is a view, showing, in perspective, details of operating connections associated with the latching bar for the carrying stops.

Figure 8 is a detail front view, showing how said latching bar is supported in the aforesaid fixed plates.

Figure 9 is a side view, illustrating means and .the operation thereof for shifting the aforesaid latching bar.

Figures 10 and 11 are enlarged side views, showing details of the novel carrying mechanism, Figure 10 showing said mechanism in normal position, and Figure 1l showing said mechanism operated to eiect the carrying" of a number.

Figures l2, 13 and 14 are each a side view of a register-bar and the train of carrying parts extending from one computing wheel to the register-bar of next higher denomination. Figure l2 shows a computing wheel directly engaged with the register-bar for addition, and also shows a register-bar in advanced position without having carried. Figure 13 is similar to Figure 12, but shows the register-bar advanced for carrying. Figure 14 shows a computing wheel not directly connected to the register-bar rack, but connected thereto by the intermediate pinion to reverse the rotation of said wheel for subtraction, Figure 14 also showing the register-bar advanced for carrying, and, compared with Figure 13, showing that the carrying advance of a register-bar is the same for subtraction as it is for addition.

Figures 15 and 16 are partial plan views 0f means forming the power-drive shown in Figure 2.

As seen in Figure 1, the novel computing mechanism co-operates with a typewriter in which numeral-keys I0 mounted on key-levers II may, through other members of the usual type-action, cause types I2 to print against a platen I3. Said platen I3 is in a carriage I4 traveling on rails I5 and I6 of the typewriter-framework I1. By operation of the type-keys said carriage is propelled in letter-feeding steps determined by an escapement-mechanism I8 under control of said keys and spring-motor I9.

The computing mechanism may include one or more sets of computing wheels 20, Figure 4, indieating four sets of computing wheels. For each computing wheel there is a register-bar 2I carrying a series of downwardly-settable index-pins 22, for the digits from 0 to 9. As disclosed in my co-pending application, Serial No. 82,226, filed January 19, 1926, (now Patent No. 1,869,582, dated August 2, 1932) only one pin at a time may be set in a bar, the setting of one pin in a registerbar being effective to force any previously-set pin in said bar back to its normal position by means represented by cam--blocks not shown, interposed between the stop-pins and fully described in said co-pending application No. 82,226, the camblocks, briefly explained, being displaced longitudinally of the register-bar upon depression of any pin, and by reason of their cam-formations being capable of restoring a previously-set pin as they are displaced. The 0 pin in each register-bar is normally set, and is, of course, restored by the setting of any higher pin in a register-bar.

For setting an index-pin in any register-bar, each numeral-key lever II has depending therefrom a stem 24, to rock 'a shaft 25, each key-lever having its own shaft. The several shafts are for actuating parallel motion pin-setting linkages 26, one for each numeral-key. Each linkage includes a pin-setting bar 21 movable edgewise and downwardly upon operation of said linkage by its numeral-key.

The pin-setting linkages are of the type shown in the aforementioned patents to Minton and Hanson. Each pin-setting bar 21 is connected at each end to a horizontal arm of a bell-crank, not shown, vertical arms of said bell-cranks being connected to the ends of an upper bar 28. Arms 29 connect the rock-shafts 25 to the upper bars 28 of their respective linkages, each shaft also having fast to its end a horizontally-extended arm 30 engageable by the numeral-key stem 24.

Index-pins are set in the register-bars as the carriage moves predetermined zones of a worksheet past the printing point. As indicated in Figure 1, downward movement of a `pin-setting bar 21 is ineifective to set a pin in a register-bar unless the bar is slightly advanced to bring the pins therein under the pin-setting bars 21. This advance is accomplished seriatim for the several register-bars by the movement of the typewritercarriage I4 in presenting the aforesaid work-sheet zones to the printing point. To this end, said carriage may carry tappets 3I settable along rails 32 of said carriage according to the location of zones of carriage travel in which index-pins are to be set. By the step-by-step movement of the typewriter-carriage I4 in such zone, a tappet clisplaces, in seriatim order, the ends 34 of jacks 35, and thereby depresses push-rods 36, to rock levers 31, each lever having one arm 38 connected to a push-rod as shown, and another arm 39 connected to one end of a transposing linkage 40, the other end of said linkage 40 pushing upon a pin 4I projecting from the side of a corresponding register-bar. According to the usual practice, the tappets 3| are offset from one another, see Figure 1, each tappet being mounted on a dog 33. By such offsetting one tappet is effective on only one set of jacks and ineffective on other sets of jacks 35, according to which set or sets of register-bars 2I shall be indexed.

With the typewriter-carriage I4 in a computing zone, a push-rod 36, corresponding to the column of the work-sheet zone which is at the printing point, will have been depressed by means of the tappet 3|, and the register-bar 2I 'connected thereto will be advanced, so that its index-pins 22 are under the pin-setting bars 21. Operation of a numeral-key now will cause the corresponding pin-setting bar 21 to descend and set a corresponding index-pin 22. The carriage I4 then escapes, releasing said push-rod 36 and causing the corresponding register-bar to be retracted by means of a spring-device 42. In the meanwhile, the push-rod 36 for the next column will have been depressed as the carriage took its letterfeeding step and the next register-bar will have been advanced to bring its index-pins under the pin-setting bars. In this manner is the pinsetting accomplished seriatim for the registerbars as the carriage moves a computing zone of the Work-sheet, column by column, past the printing point.

The transposing linkages transpose thev seriatim order, in letter-feeding direction, of push-rod operation into the proper but reverse order of the seriatim indexing of the registerbars, each linkage 40 including a bell-crank 413a which engages the pin 4I.

The index-pins 22 are set into the path of register-bar-engaging iingers 43 formed at the upper ends of levers 44, carried by a cross-bar 45 movable forward and back for advancing the register-bars and returning the advanced bars. The purpose of said levers, which is to provide for extra carrying advance of the register-bars, and the co-operating parts, will be explained further on.

For moving the cross-bar 45 in the direction in which it is to advance and return the registerbars 2l, there are employed the usual racks 46 guided for reciprocatory endwise movement along the inner sides of side members 41 of the computing-mechanism framework. Said racks 46 carry plates 48 provided with slots 49 in which tenons 50 at the ends of said cross-bar are inserted. Said slots 49 are longer than is the width of said tenons, so that the cross-bar may slide edgewise in said slots for a purpose to be explained. By moving both racks 46 in unison, the cross-bar 45 may be moved without skewing, and, 4to this end, said racks are coupled by a cross-shaft 52 journaled in said framework side members V41, and having gear-sectors 55 fastened thereto, one at each end of said shaft, alined with said racks 45, see Figure 4. Said gear-sectors are not directly connected to the racks, but 5 are connected thereto by intermediate pinions 54, mounted on the side members 41, to give the racks. 45 the right direction of movement in respect to reciprocatory rotation of the crossshaft 52, which may have connected thereto an l0 operating handle (not shown), for hand operation of the computing mechanism. For operation by power, there may be used the power-drive shown in the patent to F. A. Hart, No. 1,171,403, dated February 8, 1916, said mechanism presenting a driver 55, which, driven by a crank (not shown), reciprocates forth and back in the direction of movement of the racks 45 and registerbars 2|. Connection between said driver 55 and the racks 45 is made by means of the usual member 55, which embraces said driver, as seen in Figure 1, and which is fastened to the under side of the left-hand rack 45, said driver being positioned sidewise of the machine to align with said left-hand rack 45. For disengaging the power-drive, the casing 5I, from which the driver 55 projects, may be lowered in the usual manner, to thereby withdraw said driver 55 from the member 55. When the driver 55 is thus withdrawn, the computing mechanism may be hand operated by means of the aforesaid handle (not shown).

By means of the usual key-operated clutch not shown herein, but shown in said Hart patent, the driver 55 is normally disconnected from the motor-drive and is stationary in the position shown in Figure 1. By means of said clutch and its controlling key, the driver is connected to the motor-drive long enough to impart just one forth-and-back movement to said driver and hence to the cross-bar 45.

When the cross-bar 45 has advanced and carried the register-bars 2l forward, to extents determined by whichever digit-pins 22 were set, in the several register-bars, there must be a suitable period of time during which certain carrying operations may take place, as will hereinafter be explained. That is, said cross-bar 45 must not immediately start its return movement after completing its advance movement, because such immediate return movement would in some cases return certain register-bars 2| before they had time to "carry. To hold the cross-bar 45 stationary for a sufficiently long carrying period, the last portion of the forward stroke of the driver 55 and an initial portion of the return stroke of said driver are rendered ineffective to move the cross-bar 45, said driver 55 moving forth and back as usual, but the time-period of said portions of its strokes being apportioned to said carrying operations. It is to this end that said cross-bar is movable edgewise in its retaining slots 45 of the rack-plates 45, it being understood that said plates 45 will movewith the driver 55 throughout the full range of movement of said driver, and that the cross-bar 45 alone is held stationary Just before and just after said driver 55 completes its forward stroke. For thus holding said cross-bar 45 stationary, there may be mounted and fastened on each framework side member 41 a plate 51, in which is formed a camslot 55, the plates being disposed, as best seen in Figure 4, between the racks 45 and the walls of the side member 41. On each rack 45 there is pivoted at 55 on a suitable stud, as shown, a bellcrank lever 55, having a horizontal arm 5I for engaging the cam-slot 55 and an upright arm 52 connected to the cross-bar by a link 55, the latter having a pivotal connection 54 to said arm 52. The horizontal arm 5i carries a roll 55 for engaging the cam-slot 55. The arms 5I, 52 of said lever are on opposite sides of the rack 45 and are Joined by a cross-piece 55 (Figure 4) forming part of said lever 55. The link 53 is attached at one end to the cross-bar by screws 51, there being provided suilicient play between the sides of the slot 45 and the tenon 55 to avoid binding between said tenon and slot as the lever 55 rocks.

The range of forth-and-back movement of the driver 55 may, as in the case herein illustrated. be Just enough for full advance and return of the register-bars 2l. In such case, if the aforesaid portions of driver-movement preceding and following its most advanced position are rendered ineffective to move the cross-bar 45, so that there may be afforded time for carrying, it follows that said cross-bar 45 must in some other manner still receive the same extent of movement as the driving member 55. To compensate for the idle portion of the forward movement of the driver 55, the camslot 55 is sloped downwardly at 55. 'I'his downward slope through the medium of the lever causes an advance of the cross-bar 45, relatively to the racks 45 and plates 45, sufllcient to compensate for the movement lost through the idle portion of the forward stroke of the driver 55. When said driver starts its idle portion of stroke. it is rendered ineffective to further advance the cross-bar 45. 'Ihis is accomplished by a reverse movement of the lever 55. the cam-slot 55, to this end, including an upturned portion 15, so formed that the cross-bar 45 is held stationary because of the reverse movement imparted to the lever 50 by said upturned portion 15 while the driver 55 completes its forward stroke. As the driver thus completes its forward stroke, the roll 55 will have reached the position shown in full lines in Figure ll. The broken lines, indicating the roll 55 and the driver 55, indicate, with reference to the fullline positions of said roll and driver, some measure of the idle part of the stroke of said driver 55. It will be evident that at the beginning of the return stroke of said driver 55, there is also an idle portion in which the cross-bar 45 is not moved while the roll 55 rides down the cam-slot portion 15 with consequent rotation of the lever 55. Also, in said return movement of the driver 55, the cam-slot portion at 55 will be eective to extend the return movement of the cross-bar `45 sumclently by means of said lever 55 to fully restore the register-bars 2l. The cross-bar 45 in its fully returned position may abut stops 55', Figures 4, 10 and 11.

Another form of cross-bar-driving mechanism is indicated in Figures 2, l5, and 16. In this latter form, the revolution of a roller 13, driven in a circle by a motor 14, is translated into reciprocatory movement of the cross-bar 45 by means of a link 15 fastened to said cross-bar and projecting rearwardly therefrom. The link 15 has at its rear end a head 15 forming a face 11 which the roller 13, revolving in the direction of the arrow, Figure l5, may engage to push the link 15 forwardly, said roller 13 in its initial position being as indicated in Figure 16. When the revolution of the roller 13 has advanced the link 15 suiliciently, said roller idly passes a curved portion 15 of the face 11, said curved portion 15 being at this time concentric with a stud 19 about which said roller 15 revolves on a plate 55.

The period of this idle movement of the roller 13 before it begins to retract the link 15 and cross-bar 45 is utilized to insure in this form of drive the completion of carrying operations, 5 already mentioned. The cross-bar 45 is, where this form of power-drive is employed, fixed in the plates, designated in Figures 2 and 15 by reference numbers 48B, no movement of said cross-bar relative to said plates being required. As seen in Figure 15, the curved portion 18 is preferably so designed that the idle movement of the roller 13 may be about evenly apportioned on either side of the extreme forward position which said roller reaches, the length of l5 said curved portion 18 depending on the time interval to be allowed for carrying beforeretraction oi.' the link 15 is commenced. Figure 15 indicates by the broken circle at the right the position of the roller 13 at that point of its revolution about the stud 19 where it commences the return of the link 15. For returning the link 15 the roller 13 reacts against a face 82 of said link. Inasmuch as the roller 13 in that part of its revolution in which it moves forward can have no effect on said face 82, the latter does not extend beyond the position from which said roller begins its forward movement. Moreover, by thus limiting the extent of the face 82, it is feasible to move the cross-bar 45 forwardly independently of said roller, as in hand-operavtion, in which case the normal position of the roller may be as indicated in Figure 16. The face 82 may for a portion of its length be concentric with the curved portion 18 of the face 11, thereby giving acceleration to the final part of the return movement of the link 15 and keeping the roller 13 in contact with the face 11--18.

The roller 13 revolves only when the registerbars 2| are to be advanced for the accumulation of a number and returned, and is, to this end, connectible to the motor 14 by a clutch (not shown) such as is shown in the aforesaid patent to F. A. Hart, which clutch with reduction gearing 83 may be enclosed in a casing 84 extending from the motor 14 and which may carry the aforesaid stud 19 around which the roller 13 revolves and which stud is spaced from the driven clutch-shaft 85, for arrangement of the parts as indicated. Said shaft 85 maybe connected to the roller-carrying plate 80 by a pinion 86, fast to the shaft 85, and a meshing pinion 81, fast to the plate 80. The motor 14 may be supported on a base 68 of the computing machine.

Each computing wheel 20 has fastened thereto a pinion 89. As seen in Figure 12, the pinions 89 may mesh with racks 90 formed at the forward ends of the pin-bars 2|, or, as seen in Figure 14, the pinions may be driven by said racks 90 through intermediate pinions 9|, which may be permanently in mesh with the racks 90. As indicated in Figures 1 and 10, the computing-wheel pinions, and hence thecomputing Wheels, are normally disengaged from'both the pin-bar racks 90 and the intermediate pinions 9|. Direct engagement of the computing wheels with the racks causes them to revolve clockwise during a forward movement of the pin-bars 2|. On the other hand, if the computing wheels be driven through the intermediate pinions 9|, during said To forward movement of the pin-bars 2|, their rotation will be counterclockwise. One direction of rotation of the computing wheels may be for addition, and the opposite direction may be for subtraction. According to the arrangement of 7 5 the dial-wheel numbers, as herein indicated, the

clockwise rotation of the computing wheels, when directly driven by the racks 90, corresponds to addition, and the counterclockwise rotation of the wheels, when driven through the intermediate pinions 9|, corresponds to subtraction. 5

To shift the computing wheels 20 either downwardly for engagement with the register-bar racks 90, or rearwardly for engagement with the intermediate pinions 9|, said wheels 20, independently rotatable on a spindle 92, are retained 10 with said spindle in a shiftable frame 93 having side plates 94 spaced apart so that the ends of said spindle 92 may be Journaled therein. Said side plates 94 may be spaced apart by a crossmember 95, and by the spacing aorded by the 15 series of computing wheels and the hubs or collars 96 adjacent to the outer computing wheels. The computing-wheel frame 93 is held against lateral displacement between fixed plates 91, which may be secured to, and project upwardly 20 from, a front cross-member 98 of the comput ing-mechanism framework, said cross-member 98 serving with a rear cross-member 99 to space apart the aforesaid side members 41 of said framework. 25

For supporting the computing-wheel frame 93 between said fixed plates 91, so that it may be shifted, there may be used a cross-rod |00 supported by and spanning said plates 91. Slots |0| at the rear end portions of the computing- 30 Wheel-frame plates 94 embrace said cross-rod, and when the computing-wheel frame is in normal position, in which the computing wheels 20 are disengaged, said slots |0| extend in a horizontal direction. The forward portion of the com- 35 puting-wheel frame may be supported on arms |02 projecting from a rock-shaft |03, each computing-wheel frame being provided with one of said arms, as shown in Figure 4. Each arm |02 has a slot |04 which, when the frame 93 is in 40 normal position and the computing wheels are disengaged, extends in a horizontal direction. Said slot |04 embraces the cross-member 95 of the computing-wheel frame.

From Figure 1 it will be seen that the slots |0| 45 and |04 guide the frame for rearward and forward shifting, the rearward shifting being effective to engage the computing wheels with the intermediate pinions 9|, the forward shifting of said frame conversely disengaging the comput- 50 ing wheels from said intermediate pinions 9|. Figure 14 indicates the computing wheels engaged with said intermediate pinions.

From Figures 1 and 11 it will also be seen that the frame 93 may turn about the cross-rod |00 55 as a fulcrum, such turning being effected by rocking the shaft |03. In this case the comput-A ing wheels 20 will be directly engaged with the pin-bar racks 90, as indicated in Figures 11, 12 and 13. 60

Preparatory to the forward movement of the register-bars 2|, the computing wheels are brought into engagement with either the registerbar racks 90 or the intermediate pinions 9|, and similarly, preparatory to' the return movement of the register-bars, the computing wheels are disengaged again so as not to be reversed by the return movement of said register-bars.

Selective connections (not shown), for coupling the driving mechanism of the computing machine to the rock-shaft |03 or to a link |06 may be provided for effecting shifting of the computing-wheel frames 93 at the proper times during a computing-machine cycle. The rock-she"- -f |03 may be split into individual rock-shafts, one for each of the registers, to control the registers independently, or there may be one rock-shaft common to all the registers, and it will be understood that said selective connections may be made accordingly. Such selective connections predetermine whether the computing-wheel pinions 83 are to be presented directly to the racks 30 as for addition,- or whether they are to be presented to the intermediate pinions 3| as for subtraction. The fixed plates 31 may have two-way slots |01, into which the computing-wheel spindles 32 may extend. so that their ends may receive screws 31, whose heads bearing against the outer surfaces of said plates 91 serve to retain said spindles endwise. Horizontal and vertical branches of said two-way slots |01 serve to hold the frames 33 against displacement transversely of said branches. v

As already stated, the levers 44 on the generaloperator cross-bar have register-bar-engaging fingers 43 for pushing the register-bars forward. How said levers I4 and their register-bar-engaging ngers operate to advance the registerbars 2| extra unit-spaces for carrying, will now be explained. Said levers u, of which there is one for every register-bar, may be mounted on a common fulcrum-rod |08, and there may be one such fulcrum-rod for every set of register-bars of the computing mechanism retained between ears |03 of a bracket H0 secured to the crossbar l5, said ears projecting downwardly and forwardLv from said cross-bar. 'I'he levers 44, individually rockable on their fulcrum-rods, are spaced apart and located, as by collars or hubs III, Figure 4. The register-bar-engaging fingers 43 of said levers M are aligned with the pins 22 of their respective register-bars, and may be formed by tabs bent at right angles to said levers.

'I'he carrying of a tens value from one computing wheel to a wheel of next higher denomination is, according to the present invention, effected by advancing the register-bar for said higher wheel an extra unit-space, the extra advance being effected by causing the lever 44 to be rocked counterclockwise from the position seen in Figure 12 to the position seen in Figures 11, 13 or 14. As seen 'in Figures 10 and 12, a register-bar-engaging finger I3, backed by the cross-bar 45, may advance a register-bar by engaging a depressed pin 22. 'Ihe advance of the cross-bar l5 and hence of the fingers I3 thereon, when abutting the forward side of said cross-bar, is always to the same extent. and the extent' of advance of a registerbar therefore depends upon which index-pin is depressed. If the 0" pin, which is the first pin from the front of the machine, is not displaced from its normally-depressed position by the setting of a higher pin, the register-bar will not be advanced, because the position which the crossbar. with the corresponding nger 43 bearing thereagainst, reaches at the end of its advance movement is such that said finger 43 just touches the depressed 0 pin.` If a "1 pin is depressed, the register-bar will be advanced until said "1 pin is in the position from which the 0" pin moved in such advance of the register-bar. Similarly,- by depression of a higher pin, the registerbar will be advanced until said higher pin is in the position which the "0 pin left in said advance.

Thus, it will be seen that, irrespective of the value of the depressed pin 22, the depressed pin and is caused to abut the forward side of the depressed pin as a register-bar carrying said pin reaches the end of its advance position.

Two conditions govern the application of the stops H2, one condition being that said stops must be individually shiftable to permit an extra carrying advance of their respective registerbars, the other condition being that said stops. when the computing mechanism is in its normal condition, that is to say, when the register-bars are not being advanced to accumulate a number, must be sufficiently removed from the normally depressed "0" pins to permit the aforesaid slight advance of the register-bars seriatim during the indexing of the register-bars.

To these ends, the register-bar stops ||2 may be formed on the rear ends of elongate bars H3, which are to be shiftable simultaneously from a normal position, indicated in Figure l, wherein the stops I I2 are far enough removed from the depressed 0 pins, as seen in Figure 1, to permit the aforesaid seriatim advance of the register-bars, to the position indicated in Figure 12, and more clearly indicated in Figure l0 by the dot-and-dash outline of a stop I I2, in which latter position the stops H2 may abut the depressed pins of the advanced register-bars or the "0" pins of the register-bars that are not advanced. From said latter position, the bars H3, and hence the stops H2, are to be individually movable in a forward direction to permit an extra carrying advance of the corresponding register-bars, the forward carrying movement of the bars H3 being limited, however, so that the stops H2 are also eilective to prevent overthrow of the register-bars when said register-bars carry. The forward carrying movement of any bar I |3 is also utilized to eiect, as will be explained, a carrying displacement of the corresponding lever M and its register-barengaging ilnger 43.

To these ends, the bars I I3 are urged forwardly by individual springs H4, but are normally latched in non-carrying positions over a transverse latch-bar H5, each bar I |3 having a latching edge H8, which normally abuts the rearward edge of said bar H5. The several bars ||3 `are pivotally connected at their rearward ends to upstanding arms of levers H0 of the rst order individually rockable on a fixed fulcrum-rod I I9. Arms |20 of said levers I I0 extend, in the normal positions of said levers as seen in Figure 1, downwardly and rearwardly. To eiect rearward movement of all the bars H3 to bring the stops .H2 from the positions seen in Figure 1 to the position seen in Figure l0 or 12, in which latter position the stops are effective to prevent overthrow of the register-bars, the latch-bar H5, together with all the bars I3 latched thereover, is advanced rearwardly during the advance movement of the cross-bar I5 as will later on be explained. As the bars H3 are so moved simultaneously, their levers H0, mounted on the fixed fulcrum-rod H9, are rotated clockwise, so that the arms |20 of said levers H8 are shifted from the position indicated in Figure 1 to the position indicated in Figure 12. Said latter position of the arms |20 is such that pins |2| therein just abut downwardly-extending arms |22 of the corresponding levers 44 on the cross-bar 45 when the correspondingregister-bars register a noncarrying advance, as indicated in Figure 12. From Figure 12 it will be seen that, with the arm |22 abutting the pin I2| and the register-barengaging finger 43 abutting the cross-bar 45, and the bar I I3 latched over the bar I I5, a regislO ter-bar whose depressedpin 22 is closely confined between the stop I I2 and finger 4 3 is secured not only against overthrow, but is also secured against rebound.

Referring to Figures and 11, it will be further 15 seen that upward displacement of the forward end of one of the bars ||3 will cause said bar to move forwardly under the pull of the spring ||4. As a bar ||3 thus released from the latch-bar ||5 moves forwardly, it rocks its lever I |8 counterclockwise to the position seen in Figures 1l, 13 and 14, and which position may be determined as by abutment of the lever I I8 against a transverse rod |23 supported by and spanning the fixed plates 91 of each register. It will be evident that a lever ||8, thus rocked counterclockwise by release of its bar ||3, will also cause the corresponding lever 44 on the cross-bar v45 to be rocked counterclockwise. thereby causing the reg- 30 ister-bar-engaging finger 43 on said lever 44, and hence the corresponding register-bar itself, to be advanced in respect to said cross-bar 45. Thus each register-bar may receive an extra movement depending upon the release of a bar |I3. To prevent the levers 44 from falling into a disabling position when not engaging an index-pin 22, as, for example, when the cross-bar 45 is fully returned, each lever 44 may have an arm |24 to limit its counterclockwise movement, as is indicated, Figure ll, by the abutment of said arm with the bracket I I0 attached to said crossbar 45.

The release of a bar ||3, as aforesaid, is'to be effected every time a computing wheel, of next lower order to the register-bar controlled by said bar II3, passes its carrying point, and each computing wheel has therefore, projecting from its periphery, a carrying tooth |25. On account of the different positions of the computing wheels in addition and subtraction, the carrying teeth |25 of the several wheels operate to release the bars I I3, preferably through intermediate carrying levers |26 individually rockable on a fulcrum rod |21 supported between the side plates 94 of the computing-wheel shift-frame 93, and spaced and located on said rod |21 as by collars or hubs |28, Figure 11. Each carrying lever |26 has a cam-shaped arm |29 arranged so that said carrying lever may be rocked by the carrying tooth |25 in either direction of rotation of the computing wheel. As .a carrying lever |26 is rocked, the end of an arm |30 thereof moves upwardly against and displaces the forward end of a corresponding bar II3, and thus releases said bar II3 from the latch-bar ||5.

The location of the ends of the arms |30 of the levers |26 is so arranged with respect to the cross-rod |00 that said ends of the arms |30 describe an are or line when the computing-wheel shift-frame 93 is swung around said cross-rod |00 for engaging the computing wheels directly with the register-bar racks 90, which is substantially the same as the line along which said ends of the arms |30 move as the computing wheels are shifted rearwardly with said frame 93 for engagement with the intermediate pinions. Thus the carrying levers |26 are effective in either adding or subtracting position of the computing wheels 20, to release their respective bars I3.

A carrying train from any computing wheel to the register-bar of the computing wheel of next higher denomination includes the carrying lever |26 actuated by the former computing wheel, the bar I I3, releasable by said carrying lever |28, the lever ||8, connected to the rear end of said bar ||3, and the lever 44, controlled by the latter lever II8, the register-bar engaging finger 43 of said lever 44 being aligned with the pins 22 of the register-bar ofthe computing wheel of said next higher denomination. Thus, one end of said train is the armI29 of the carrying lever \I26, and is adjacent the computing wheel of lower denomination, and the other end of said trainis the register-bar-engaging finger 43 for the register-bar of next higher denomination. The required offset of said ends of the train may be eifected by forming and arranging the parts thereof as indicated in Figures 4 and 5. As indicated in Figure 5, the carrying lever |26 may be within the plane of rotation of the carrying tooth |25. The forward portion of the bar ||3 is aligned with said lever |26, the rear portion of said bar being offset to the left by bends |32 and having the stop4 I|2 formed by a tab bent to the left to align with the pins 22 of the register-bar of next higher denomination. The lever I|8 is pivoted on the left side of said bar ||3 and its pin |2I projects to the left to align with the arm |22 of the lever 44 for said registerbar. Said lever 44 has its finger 43 in the form of a tab bent as shown to align with said pins 22 of said register-bar.

Each bar |I3 is connected to its lever I I8 by a headed pivot-stud |33. The levers II8, individually rockable on their fulcrum-rod ||9, may be spaced and located on said rod as by hubs or collars |34, each register having one of said rods which is supported by and spans the xed plates 91. Although the units register-bar never carries, it is nevertheless provided with a bar II3, a lever 8 and a lever 44, the later having its register-bar-engaging finger 43, inasmuch as these parts also prevent'overthrow and rebound of the units register-bar. No carrying train extends from the computing wheel of highest denomination, which is the first Wheel from the left of the register.

In most cases, the levers 44 are rocked positively by the positively-driven movement of the cross-bar 45 itself when carrying is to be effected and therefore an extra carrying advance of a register-bar is effected positively. That is to say, in most cases carrying bars I|3 will have been released, and the levers H8, connected thereto, will have been rocked before the crossbar 45, with its register-bar-engaging levers 44, effects contact of the arms |22 of said latter levers with the pins |2| of the arms |20 of levers ||8. Thus, said arms |20 and their pins I2I form interponents which, by the release of their respective bars ||3, are thrust into the path of the advancing cross-bar levers 44 on the cross-bar 45. It will be seen, therefore, that as the arms |22 of the cross-bar levers encounter the pins |2|, thus thrust into said path, the crossbar levers 44 will be caused to rotate counterclockwise to an extent equivalent to advancing their register-bars an extra unit-space, and which extent, it will be understood, may be determined by suitable proportioning and arrangement of the parts as illustrated in the drawings. In those cases where a carrying advance of a register-bar is eected, after said register-bar has reached its advanced position, as indicated in Figure 12, the necessary carrying displacement of the parts involved is eii'ected by the power ail'orded by the spring II4.

The lever H3, whose arm |20 is thus thrust into the path of the advancing cross-bar lever 44, is to be stabilized against counter-rotation while it co-operates to rock said cross-bar lever 44, and the later lever 44 is also to be locked against counter-rotation after it has been rocked to the position of Figure 11, 13 or 14. To this end the arm |22 of the lever 44 has an edge |23 extending in such direction relatively to the fulcrum of the lever I0 and clearly indicated in Figure 12, that said lever ||0, if it is caused to be rocked by unlatching of the bar ||2, may correspondingly rock the cross-bar lever 44. At the end of this rotation of the two levers 44, ||0, the pin |2| of lever ||0 arrives opposite a scooped-out portion |21 of said edge |20. A point or hump |20, at the intersection of the edge |20 and its scooped-out portion |21, ail'ords such point of contact with the pin |2| as the lever 44 reaches said pin after the latter has already been thrust out, as aforesaid, that the lever 44 is rocked counterclockwise while the cross-bar 45 is completing its advance movement.

As indicated in Figure l1, said point or hump |20 approaches and makes contact with the pin |2| on the dot-and-dash line |33. In the ensuing rocking of th'e lever 44 to the position shown in Figure 11, 13 or 14, as the point or hump |33 is thus arrested while the cross-bar completes its advance, it will be seen that the line of reaction afforded by the lever ||0 is to be substantially through or on a favorable side of the fulcrum-center of said lever, and hence there is substantially no tendency to rock said lever contrariwise, and therefore there is substantially no tendency to relatch the bar ||2.v As the lever thus, in the latter case, is rocked to the position shown in Figure 11, the scooped-out portion |31 settles against the pin |2I. Since said portion |31 may, at its final point of contact with the pin I2|, be substantially perpendicular to the aforesaid line of reaction through the fulcrum-center of the lever ||8, as is clearly indicated in Figure ll, the lever 44 is also secured against counter-rotation after it reaches said position, and hence there is no tendency to rebound of the register-bar, even when said bar receives an extra advance for carrying.

The stop-bars ||3 are spaced laterally and guided at their forward ends by a slotted transverse bar |40, which may also have slots |4|, in which the front portions of the register-bars 2| are guided. The stop-bars ||3arenotchedattheir front ends to form an upper branch H3* which is received by a slot in said transverse bar |40 and a lower branch ||3 which underlies said transverse bar to limit the upward movement of the forward end of a stop-bar |3. Said register-bars may be guided at their rear portions in slotted transverse plates |42, secured to the crossmember 33 of the framework. Said transverse bar |40 may be retained between the xed plates 31, which retain the computing-wheel frame 33 against lateral displacement. Each pair of said fixed plates may have rearward extensions |43, between the ends of which may be retained the fixed fulcrum-rod I3 and abutment-rods |20 of the levers ||3.

Each of a pair of said fixed plates 31 may have a slot |44, the opposite slots of the pair of plates serving to retain the latch-bar I5 whose ends may be guided in said slots, as indicated in Figures 5 and 8. The shifting of said bar back and forth in said slots |44 is effective not only to bring the register-bar stops ||2 into and out of their stopping positions, as aforesaid, but the forward shifting of said latch-bar ||5 is also effective to cause the relatching of those stop-bars ||2 which have been released. With the position of the parts as seen in Figure 1l, 13 or 14, in which the released bars ||2 are held by abutment of their levers ||3 against the rod |22, it will be evident that shifting of the latch-bar ||5 forward, that is. toward the left, to the position indicated in Figure 1 or l0, is effective to relatch the released bars.

All of the latch-bars ||5 of the several registers are thus shifted back and forth simultaneously, and, to this end, are connected to a universal bar |41, which extends across the machine to span the several registers, as shown in Figures 4 and 5, the ends of said bar |41 slightly overlapping the outer side plates 31 of the first and last registers. Movement of the universal bar |41 back and forth is transmitted from the crossshaft 52, which, as previously explained. has a reciprocatory rotation, resulting from its connection with the general-operator racks 40. To move the universal bar |41 back and forth without skewing, it is engaged at two widely-spaced places along its length by a pair of slides |40, which may be shaped as best seen in Figures 3, 5 and 9. The forward end of each slide |40 has a slot |43 which slidably fits a block |50, located and riveted within a slot |5|, cut in a post |52 upstanding from the cross-member 30 of the framework and secured to said cross-member by a screw |54, Figure 3. The sides of the slot |5| retain the forward end of the slide |43 laterally, while the block |50 cooperating with the slot |40 in said slide retains the forward end of said slide vertically. The rear end of the slide |40 has a slot |52 which slidably fits a rectangular block |55, which is provided with a hole for a running fit on the cross-shaft 52.

For enabling the cross-shaft 02 to reciprocate the slides |43, there is fastened to said shaft two cams |55, one cam being adjacent each slide |40. 'I'here is secured to each slide |43 a closure-plate |51, having a slot |53. Said closure-plate is secured to its slide |43, by screws |53, on the side opposite to which the cam |55 is disposed. There are on each slide |43 a front cam-roll |30 and a rear cam-roll IBI, the former being directly mounted on said slide on a headed stud |02, and the latter roll |5| being mounted on the closureplate |51 by a headed stud |52.

The front roll |30 has an outer flange |04, which may bear against the side of the cam |50 to co-operate with the closure-plate |51 in retaining the slide laterally. For such lateral rstention of the slide, the top and bottom edges of the slot |53 of the closure-plate overlap the top and bottom edges of the slot |52 in the slide |40, so that said closure-plate bears on the side of the block |55 which in turn bears on one side of the cam |55 which thus retains said slide laterally, the roll-flange |54 bearing on the other side of said cam.

For coupling the slide |43 with the universal bar |41, each slide |40 may have a notch |05.

,. tions for attaching which includes at its forward side a tongue |68, which may overlap and underlie the forward edge of the universal bar, and thereby 'serve to retain the latter at said forward edge. For easy assembling of the parts, the rearward side |65 of the notch |85 is spaced from the rearward edge of the universal bar, the latter being secured at said rearward edge, however, by means of a block |81 formed as best seen in Figures 3 and 5, said block including a forwardly-projecting tongue |50 which overlaps and underlies the rearwardedge of said universal bar. The block |81 is slotted at |69 to embrace the sides of the slide |48, and close the gap between the rearward side |652* of the notch |85 and the universal bar |41, said block being secured in place by a screw4 |10.

Connection is made between each latch-bar I5 and the universal bar |41 by means of a pair of links |1| engaging the latch-bar ||5 near its ends, and being disposed, therefore, adjacent the fixed plates 91 which support said latch-bar atits ends, as aforesaid, by means of the slots |44. Each latch-bar `||5 may, as best seen in Figure '1, have at each end'a notch |12 to form with a notch |18 in vthe link |1| an interlocking joint connecting said latch-bar H5 and link |1|. The rearward end of each link has a slot |14 which slidably fits a stud 11i-projecting from the inner side of the adjacent' fixed plate 81. Thus, by means of said slots |14, studs |15 and the slots |44, the latch-barl and its pair of links |1| are guided for back-and-forth movement and are Wholly suppollied by the register fixed plates 91. For connection 'with'the universal bar |41, each link |1| has a notch |16, Figure 7, the frontend rear sides of which may, as seen in Figure 5, embrace said universal b ar. Each latch-bar may also carry an 'anchor-platev |11, having perforath ends of the springs ||4 that pull the stop-bars H8 forward as they are unlatched. In order 4 that the pull of said springs lllmay have 'a downward component, the anonor-plate |`|l|v is somewhat below the springends attached to said stop-bars ||3, said downward component yof the spring-pull serving to pull the forward-end of the stop-bar down when the latch-bar H5, lsrnoved forwardly, and thereby causing the stop-bar to become relatched. For thus positioning the anchor-plate |11, it is spaced from. the Vlatch-'bar 5 by collars |18, and is secured by screws |18.

Means to ensure positive relatching of the stop-bars'i, and designed to supplement the downward pull of the springs ||4, include, for each' register and the set of stop-bars I |3 therein, a swingable bail |80, having side arms |8|, whereby said bail may be pivoted to the inner sides of a pair yof xed plates 91, by pivot-screws |82, threaded into said fixed plates. Said bail |80, extending transversely of the several register-bars 2| and stop-bars |I3 of the register, is provided with slots |88, to clear said registerbars and afford prongs, the lower ends of which, reaching downwardly between the register-bars, may engage and push against the top edges of the stop-bars H3. It will be seen that if said bail |80 is pressed downwardly after the latchbar |5 has been moved forwardly for relatching the stop-bars H3, each stop-bar will be positively urged down, to ensure that the latching edge ||6 of each stop-bar ||3 will be properly caught by said latching bar ||5. For imparting such downward movement to the bail |80, the right arm |8| -of each bail is extended rearwardly to include a lug |84, which may be engaged by suitable means to effect the depression of said bail |80. Such means may be formed on a. crossshaft |85, in the form of teeth |86, which, in a revolution of said shaft, pass over and displace said lug |84, with a consequent depression of the bail |80. Said teeth may be separately inserted in the cross-shaft |85,'there being one tooth for each register, each tooth `having a stem |88, which is received by a. transverse hole in the shaft |85, and is secured by anut |89, which may be countersunk below the surface of said shaft. The shaft |85 receives a complete revolution during a computing-machine cycle to fulfill operation of means (not shown) for controlling other operations of the computing mechanism, said complete revolution being derived from the reciprocatory motions of the crossshaft 52 and left-hand rack 48.

To this end, the cross-shaft 52 is provided with an additional sector |90, which may engage a sector |9| loose on the shaft |85. Another sector |82, also loose on said shaft, is coupled to the left rack 4,8 by an intermediate gear |93, Figure 4. A clutch-device |94, disposed between the sectors |9| and |92, is keyed to the shaft |85 and is arranged to receive from the opposite rotations of said sectors |9| and |92 one continuous rotation as the cross-shaft 52 and rack 4 6 are reciprocated once in a computing-machine cycle. Details of the construction of said clutchdevice |94 and its operation with respect to the sectors |9| and |92 are fully set forth in my original application, Serial No. 324,353. The sector |9| is retained by a collar 202, fastened to the cross-shaft |85, the latter being journaled in the side members 41 of the framework. Inasmuch as the bail |80 is depressed when the latch-bar ||5 is in its forward position, restoration of said bai-1 may be effected by the rearward movement of said latch-bar ||5. To this end, the left arm |8| of said bail has a downward and rearward extension 203, whose lower end, see Figure 10, is in the path of the latch-bar 5 when said latch-bar is to be movedrearwardly. Rearward'movement of said latch-bar ||5 will therefore cause upward displacement of the bail |80 as seen in Figure 11. While the latch-bar ||5 is in said rearward position, the bail |80 is held up and so cannot interfere with upward movement of the stop-bars ||3, such upward movement taking place whenever a carrying lever |26 is operated.

The cross-shafts 52 and |85 and the generaloperator cross-bar 45 may be supported at their middle portions by a transverse bar |96, secured to and fastened to the front and rear cross-members 98, 99 of the framework. The general-operator cross-bar 45 may bear directly upon the top of said transverse bar |96. To enable said bar |96 to support the cross-shafts 52 and |85, each of the latter is' provided with a grooved collar |91, which may have a running fit on its shaft, and one ange of which may bear upon the upper edge of an angle-piece |98, secured to and extending upwardly from the transverse bar |96. The grooves of said collars |91 receive slots |99a formed in a plate |99, which is attached to the upstanding side of the angle-piece |98 by screws 200. The plate |99 and grooved collar |91 constitute middle bearings for the shafts 52, |85, which may be easily dismantled or reassembled to facilitate removal or installation of either shaft 52 `or |85. It will further be noted that the arrangement of the slides |48 and of the mounting and operating means therefore is also condueive to easy assembly and disassembling of the parts. Furthermore, any register may be easily removed when the screws 20|, which secure it to the cross-member 92, Figure 10, are removed. The bar |41 may be retained against endwise displacement by two pins |41* projecting upwardly therefrom and abutting the sides of the transverse bar |94.

The contours of the cams |54 may be so arranged that the latch-bars ||l and the bars IIS, the latter having the register-bar stops ||2, are shifted forwardly gradually. but soon enough to bring the stops ||2 into effective position before a register-bar reaches the end of its advance movement. and similarly the return of the latchbar ||5 is also effected gradually through said arrangement of the contours of the cams |55, the return of the latch-bar ||5, and consequently of the bars H3, not commencing, however, any sooner than say, the time at which the returning cross-bar 45 picks up the farthermost advanced register-bar.

Alignment and location of the teeth of the computing-wheel pinions 40 may be secured by individual spring-pressed detents 254, which fit the tooth-spaces of said computing-wheel pinions I5. Said detents 204 may be swingably mounted and spaced on the shaft or cross-member l5 and their springs 204' may be light enough in comparison with the springs ||4 so as not to unduly impede the "carrying" force of said-latter springs.

As an illustration of the operation of the computing mechanism, consider the following computing example, in addition:

The operator ilrst sees that the computing mechanism is conditioned for addition. The tappet 3| and a tabulating stop 255 having been properly set in relation to the work-sheet zone in which the ilrst item 22 is to be typed, the operator presses the appropriate denominational tabulating key (not shown), and thereby, through connections not shown, raises the corresponding denominational stop 205 to set the typewritercarriage |4 at the tens column of said sone. The item 22 is then typed on the work-sheet by operation of the numeral-keys III, and during this operation the 2" index-pins 22 are caused to be set in the tens and units register-bars 2| of whatever register the tappet 3| is set for, it being understood that if only one tappet 3| is set only one set of register-bars will be indexed, and that by setting two tappets 3|, one for one register and one for another, accumulation may be eifected in two registers. The indexing of the "2 pins in the "tens" and units" register-bars caused the 0" pins of said bars to be displaced upwardly. by means not shown but described in my aforesaid co-pending application No. 82,226. 'I'he number "22 having thus been typed on the work-sheet and corresponding index-pins having been set, the computing mechanism is now ready to be operated for the accumulation of said number in the computing wheels. To this end, the clutch-device of the power-drive is caused to be engaged by retraction of the usual clutch-trip pin, which may be operated by a suitable key and connections, said clutch-device, trip-pin, key, and connections being of the type shown in the aforesaid patent to Hart. Said clutch-device is of such character that the computing-mechanism driver 55 makes one complete forth-and-back movement and no more, inasmuch as said clutch-device in the normal operation thereof automatically disengages itself at the end of said movement, and the-cross-bar 45 therefore makes only one complete forth-andback movement. Similarly, if the power-drive shown in Figures 2, l5 and 16 be employed, the roller 1I of said drive makes only one revolution and no more, starting from and ending in the position shown in Figure 16.

In the initial portion of the forward stroke of the cross-bar 45, the computing-wheel pinions l0 are caused. by the rocking of the shaft |52, to drop into direct engagement with the registerbar racks 95. As the cross-bar 45 proceeds further in its advance stroke the "tens" and lunits register-bar-engaging fingers 42 on said crossbar engage the depressed "2 index-pins of the tens and units register-bars which are thereupon advanced two unit-spaces and the tens and umts computing wheels 2|| are also rotated clockwise two unit-spaces. Before the rack-engaging nngers 42 engaged the depressed 2" pins, the register-bar stops ||2 on bars III were caused, by the rearward movement of the latch-bar ||5. effected by its operating connections, to be moved rearwardly to the position indicated in Figure 9 or 12, and in which position said stops abut the depressed 2" pins of the fully-advanced register-bars. register-bars, the relative positions of the register-bar stops ||2, the register-bar-engaging fingers 4.2, and the cross-bar 45 in respect to the depressed "2" index-pins, are as indicated in Figure 12, from which it will be seen the advanced register-bars are secured against overthrow and rebound.

The cross-bar 45 having now fully advanced the tens" and "units" register-bars for accumulation of the number "22, said cross-bar is caused, through the effect of the cam-slot portion 10, Figure 11, or the curved portion 1l, Figure l5, to be stationary for an interval of time, this stationary period in the operation of the cross-bar 45 affording time for` carrying. No carrying operation, however, takes place during the accumulation of the number 22", it being understood that all the register-wheels were originally set at "0. The cross-bar 45 only commences its return after the roll 55 has reached, in the return movement of racks 45, the bottom of said cam-slot portion 10. Similarly, in the power-drive shown in Figure l5, after passing the curved portion 15 of the cross-bar link 15 the continued revolution of the driving roller 18 causes the cross-bar 45 to be returned.

In the initial portion of the return stroke of the cross-bar 45, the computing wheels are caused, by reverse rocking of the shaft |03, to be disengaged from the register-bar racks l0 so as not to be reversed when the cross-bar 45 picks up the register-bars. The cross-bar 45 in its return movement picks up the advanced register-bars by engaging the projections |95 thereof, and, with the co-operation of the spring-device 42, returns them fully to their normal positions, as seen in Figure 1. The cross-bar 45 itself does not move back far enough to effect the full' return of the register-bars. Said spring-device 42 completes the return of said register-bars in order to leave a gap |81 (Figure l0) which affords sumcient room for the seriatim advance of the register-bars for indexing of the pins 22. During the return stroke of the cross-bar 45 and its operating train, including the cross-shaft 52, the

At the end of the advance of said register-bar-stops II2 on bars I|3 are moved forwardly again by the advance of the latch-bar I I5 effected through its describedl operating connections with said shaft 52 to leave room between the pins and said stops for the aforesaid seriatim advance of the register-bars for pinsetting.

Near the end of the cross-bar45 return moveent, pin-restoring balls not shown, but described in my original application No. 324,353, are operated to effect restoration of the 2 pins of the tens and units register-bars by resetting the 0" pins of said register-bars.

After an accumulating cycle of the mechanism for the item 22 is thus completed, the typewriter-carriage I4 being returned either before or after said cycle and the platen line-spaced, the next number 8 is typed on the work-sheet after tabulating said carriage I4 to the units column. The 8 pin will thereby be set in the units register-bar with a corresponding restoration of the 0 pin of said register-bar, and the clutchdevice of the power-drive is tripped to again operate the mechanism to accumulate 8. During this accumulating operation, the units register-bar advances eight spaces, thereby revolving the units computing wheel also eight spaces clockwise, and causing it to pass the carrying point, inasmuch as it previously registered 2 and now registers 0. As the units wheel so passes the carrying point, its carrying tooth |25 rocks the units carrying lever |26 and releases the corresponding stop-bar I|3 to effect a forward advance of the register-bar-engaging finger 43 for the tens register-bar which is thus advanced one unit-space. 'I'he tens wheel therefore, instead of showing 2, now shows 3. In this particular example, the carrying tooth |25 of the units wheel released the stop-bar ||3 as the units register-bar was moving through its last unit-space of movement, so that the carrying advance of the tens register-bar is probably effected by the power of the spring ||4 of the released stop-bar H3, the actual carrying advance of the tens register-bar probably taking place while the cross-bar 45 is in its stationary period.

During the return stroke of the cross-bar 45 and the accompanying counterclockwise rotation of the cross-shaft 52, all the stop-bars I I3, except the one which was released for carrying and whose lever ||8 therefore already abuts the rod |23, are moved forwardly again by the for- Ward movement of the latch-bar II5, connected to said cross-shaft 52, said latch-bar passing slightly beyond the latching edge IIS of the released stop-bar, and thereby causing the released stop-bar to be latched again, as indicated in Figure 1. Similarly the latch-bar II5 also passes, it may be noted, slightly beyond the latching edges |I6 of the other bars |`|3, after the levers I I8 of said other bars in their forward movement nally abut said rod |23. In the relatching of the bars |I3 the bails |80 co-operate with the springs ||4 in forcing the bars downward, so that the latching edges I I5 are sure to be caught by the latch-bar 'I I5 when the latter moves rearwardly in a succeeding cycle. As best seen in Figure 10, the balls |80 are down when the machine is at rest in its normal position, the several bail-actuating teeth |86 being then over the lugs |84 of their respective bails. This locks the carrying bars II3 against accidental unlatching while the machine is at rest. Aside from the release and restoration of a stop-bar |I3 and its related parts for carrying, the operations of the mechanism are the same for the accumulation of 8 as were the operations for the accumulation of 22.

In the subtractive computing example 10 is first typed and indexed in the tens and units register-bars, and the computing mechanism is operated to accumulate 10 as aforesaid. 'I'he I pin in the tens register-bar, which, it may be noted, happens to be the only pin indexed, is restored at the end of the accumulating operation by resetting of the 0 index-pin. The 1 to be subtracted is now typed (the carriage having been returned and the platen line-spaced), and correspondingly the 1 index-pin of the units register-bar is set, it being noted that the pin which is set always has the same value as the operated numeral-key, irrespective of whether the item is to be added or subtracted. It may also be noted that in subtraction the zero-pin of a register-bar is also, as in addition, restored by the setting of a higher pin in said bar.

In the accumulating operation of the computing mechanism which is now to take, place, the computing wheels must be rotated reversely or counterclockwise in order that the l may be subtracted. Before a computing cycle is initiated therefore by engagement of the clutch-device of the power-drive, a subtraction-key (not shown) must be rst pressed in. By pressing in the subtraction-key, mechanism not shown, but of the type shown in my original application No. 324,- 353, is conditioned so as to be effective during the computing-machine cycle to shift the computing- Wheel frame 93 rearwardly before the registerbars advance, and then forwardly again before the register-bars return, such rearward and forward shifting of said frame 93 causing the computing wheels to engage the intermediate pinions 9| before the register-bars advance and to be disengaged before said register-bars are returned.`

The rock-shaft |03 remains stationary during the subtractive accumulating operation.

With the computing Wheels 20 moved rearwardly into engagement with the intermediate pinions 9|, the forward movement of any pin-bar 2| causes its computing wheel to be rotated counterclockwise. The units Wheel which registers 0 is therefore rotated one space counterclockwise from said 0 position to the 9 position, and thus the carrying tooth |25 of said units wheel displaces its carrying lever |26, causing the corresponding bar I I3, which extends to the tens register-bar to be released, with the result that said tens register-bar advances one unit-step forwardly. Thereby the tens" wheel, driven through its intermediate pinion 9|, is rotated counterclockwise one step or from l which it previously registered to 0, and the computing wheels as a whole now indicate 9, which is the correct result of the above subtractive computing example.

Except for the reversed rotation of the computing wheels caused by their engagement and disengagement with the intermediate pinions 9| instead of with the register-bar racks 90, the accumulating operation of the mechanism and the preparatory indexing of the pins 22 are the same for -subtracting a number as for adding a number, that is to say, the operation of the carrying trains is the same in both cases, and the restoration of the index-pins, by resetting all "0" pins, is also the same in both cases.

At the end oi a subtractive computation the mechanism may be restored to its normal additive condition by releasing the subtraction-key, whereupon the mechanism, mentioned as aforesaid as being disclosed in my original application No. 324,353, is conditioned to rock the shaft 103 during an additive computing-machine cycle.

Variations may be resorted to within the scope of the invention, and portions oi.' the improvements may be used without others.

Having thus described my invention, I claim:

1. In a computing machine, a plurality of register-wheels, reciprocatable index bars to actuate the same, extents according to the number indexed therein, a general operator to actuate the bars, and having means actuable whereby an individual index bar is actuated an extra carrying step, and carry-over means, including a pivoted lever controlled by a wheel for interposal into the path of said actuable means on the general operator, to thereby cause said actuable means to be actuated to move an index bar one carrying step in addition to the steps indexed in said bar. l

2. In a computing machine, a plurality Aof register-wheels, indexable reciprocatable pinbars to actuate the same, extents according to the number indexed therein. adjustable pins on each bar, a general operator to engage the indexed pins to actuate the bars, a member on the operator for engaging the adjusted pin of a bar, said member movable relatively to said operator, and carry-over means, including a member releasable by a wheel from a retracted position to engage said movable member and thereby cause said relative movement o! the latter to advance said bar for one carrying step in addition to the steps indexed in said bar.

3. In a computing machine, the combination with a plurality of register-wheels, oi reciprocatory pin-bars to actuate said wheels according to the pin set therein, a general operator for the pin-bars, each pin-bar having a normally set zero-pin restorable by the setting of a higher pin into the path of the general operator, individually-movable stops for engaging the set pins at the end of the advance movement of the pin-bars, carry-over means co-operative with the general operator and the zero-pin or other set pin oi' a bar to advance said bar a unit step for carrying, said stops being normally retractedl from stopping position to permit a slight advance o! the pin-bars for a certain pin-setting operation, and means operative during advance of the general operator to shift said stops to effective position before the advance of the pin-bars is completed, said carry-over means being eiIective under control oi a wheel to again cause a retraction of the stop corresponding to the pin-bar controlled by said carry-over means to permit an extra carrying step of said pin-bar, said shifting means also being reversely eiective to restore all oi the stops to their original retracted positions as before said advance oi' the general operator.

4. In a computing machine having a plurality of register-wheels, each wheel having a carryover tooth, reciprocatable wheel-rotating index bars, individually-settable index pins for each bar, and a general operator to reciprocate said bars according to the set pins, in combination with an auxiliary travel-controlling means for said bars, including a device associated with the general operator for engaging the set pin of a bar, a stationarily pivoted lever rockable to a position for engaging and thereby advancing said pin-engaging device relatively to said general operator at the advance of the latter, and means whereby the carry-over tooth of the wheel of next lower denomination to said bar may rock said lever to said position to eilect an additional carryover step of said bar.

5. In a computing machine having a plurality of register-wheels, each wheel having a carryover tooth, the combination of reciprocatable wheel-rotating index bars, individually-settable pins for each bar, a general operator to engage the pins when set and actuate their respective bars, and additional travel-controlling means for said bars, including a device carried along with thegenerai operator for engaging the set pin oi' a bar, a stationarily pivoted lever rockable to a position to engage and thereby advance said pin-engaging device from a retracted position relative to said general operator at the advance oi said general operator, a latchable arm connected to said stationarily pivoted lever, a latchmember to normally hold said arm to keep said lever in inoperative position, and means responsive to a tooth of the wheel of next lower denomination to said bar to release said arm from the latch-member to thereby eilect said movement of thepin-engaging devi relative to the general operator.

6. In a computing machine having a plurality of register-wheels, each wheel having a carryover tooth, the combination of reciprocatable wheel-rotating index bars, individually-settable pins for each bar, a general operator to engage the pins when set and actuate their respective bars, and additional travel-controlling means for said bars, including a device pivoted to the general operator for engaging the set pin of a bar, a stationarily pivoted lever rockable to a position to engage and in turn rock said pin-engaging device at the end of the advance of said general operator, a latchable arm connected to said stationarily pivoted lever, a latch-member to hold said arm and keep said stationarily pivoted lever inoperative, and a pivoted lever responsive to a carry-over tooth for the wheel of next lower denomination to said bar to release said arm, to thereby eilect said rocking of said pin-engaging device for advancing said bar an extra step.

'7. In a computing machine having a plurality of register-wheels, each wheel having a carryover tooth, the combination with reciprocatable wheel-rotating bars, indivldually-settable pins for each bar, lor controlling, at will, the distances traveled by said bars, and a general operator to engage the pins when set and actuate their respective bars, of additional travel-controlling means for said bars, including a shiftable device carried by the general operator for engaging the set pin of a bar, a stationarily pivoted lever rockable to a position to engage and move said pin-engaging device at the end of the advance of said general operator, a latchable arm connected to said lever and constituting a stop limiting the throw of said bar, a latch-member to hold said arm and keep said lever inoperative, and means responsive to a tooth of the wheel of next lower denomination to said bar to release said arm, to thereby eiect movement of said pinengaging device relative to said general operator for advancing said bar an extra step.

8. In a computing machine having a plurality of register-wheels, each wheel having a carrya carry-over step in addition to those indexed over tooth, the combination with reciprocatable wheel-rotating index bars, and a general operator to actuate the bars, of additional travel-controlling means for said bars, including a movable l device associated with the general operator for engaging an index bar, a stationarlly pivoted lever rockable to a position to engage and move said bar-engaging device relatively to the general operator at the advance of the latter, a latchable lo arm connected to said lever and constituting a stop, limiting the throw of said bar in two positions, a latch-member to hold said arm and keep said lever inoperative, and means responsive to a tooth of the wheel of next lower denomination l to said bar to release said arm from the latchmember, to thereby effect the movement of said bar-engaging device relatively to the general operator for advancing said bar an extra step.

9. In a computing machine having a plurality 20 of register-wheels, each wheel having a carryover tooth, the combination with reciprocatable wheel-rotating index bars, and a general operator to actuate the bars, of additional travel-controlling means for said bars, including a device 25 movable along with the general operator for engaging an index bar, a pivoted lever to engage and move said bar-engaging device relatively to the general operator from a retracted position at the end oi' the advance of the general operator, a latchable arm connected to said lever, a powerdriven latch-member to hold said arm and keep said lever in inoperative position, and means responsive to a tooth of the' wheel of next lower denomination to said bar to release said arm from the latch-member to eiect movement of said bar-engaging device' relatively to the general operator for advancing said bar an extra step, said power-driven latch-member movable to effect the relatching of said arm and to return said lever to inoperative position.

10. In` a computing machine, a plurality of totalizing wheels, indexable reciprocatable denominational racks to actuate the same, for extents according to the numbers indexed therein, adjustable index-pins on each rack, a reciprocatable general operator to engage the indexed pins to advance the racks for rotating the totalizing wheels, and a carry-overv mechanism including a pivoted rocker on theoperator for engaging the adjusted pin oi a rack, said rocker being movable along with said operator, a normally retracted member projectable to engage and rock said pivoted rocker near the end of the rackadvancing stroke of the general operator to thereby advance said rack for one carrying step in addition to the steps indexed in said rack, and means whereby, at every carry-over step of the wheel of next lower denomination to said rack, said retracted member is projected.

11. In a computing machine, a plurality of totalizing wheels, indexable denominational racks for rotating the totalizing wheels, and a reciprocatory general operator to drive the indexed racks, in combination with a carry-over train, normally latched -ininoperative position, carry-over-control means enabling one of said wheels to trip said carry-over train into operative carry-over position at each carrying step of said Wheel, and a member reciprocable along with said general operator and displaceable relatively thereto, said member engaging with said operatively positioned carry-over train as the general operator nears the end of its rack-advancing stroke, and being therebydisplaced to drive the rack for the wheel i5 ofnext higher denomination to said one wheel therein.

12. In a computing machine, a plurality of register-wheels, indexable racks for rotating the wheels, and a reciprocatory general operator for driving said racks, in combination with a springpressed carry-over train normally latched in inoperative position, a carry-over control enabling one of said Wheels at its every carry-over step to release said train to operative carry-over position, and a rocker pivoted to, and movable along with,

ksaid general operator, said rocker being rockable for driving the rack for the wheel of next higher denomination to said one wheel farther than the general operator, said rocker being arranged to engage with the released carry-over train near or at the end of the general-operator advance and thereby be rocked to drive said rack of next higher denomination a carry-over step in addition to those indexed therein.

13. In a computing machine having digitwheels, the combination of a plurality of reciprocatory indexable drive-racks for said wheels, a general operator for cycling said racks to rotate the digit-wheels, carry-over mechanism including carry-over members projectable from an idle position for controlling extra carrying advances of the racks, means over which said carryover members are latched in idle position and from which said members may escape individually under control of said Wheels for the carrying operations, said latching means being reciprocatable for returning and relatching the escaped carry-over members in timed relation to the cycle, and means acting between the opposite strokes of said reciprocatory latchlng means to force said latching means and carry-over members into interlocking relation, to thereby ensure the return and relatching of all of said carry-over members, said last means being conditioned during the cycle to permit the escape of said carryover members but being normally in condition to prevent accidental unlatching and escape of said carry-over members.

` 14. In a computing machine, a plurality of digit-wheels, denominational drive-racks for said digit-wheels, a reciprocatory general operator for said racks, denominational orders of settable digit-elements co-operative with said general operator for driving said racks and digit-Wheels different extents, a rack-advancer driven along with said general operator, said rack-advancer being movable also relatively to said general operator and co-operative with a set digit-element or one of said racks for driving said one rack farther than said general operator for carrying, carry-over-control means projectable from a retracted position to a carry-over position to enable and cause said carry-oVer-control means to act against and thereby displace said rack-advancer relatively to the general operator when the latter is near the end of its rack-advancing stroke, and thereby cause said one rack to be driven a carrying step farther than the general operator, and means whereby the digit-wheel of next lower denomination to said one rack projects said carry-over-control means at every carry-over step of said wheel.

l5. In a direct-subtraction key-set computing machine, the combination of a group of digit-wheels having carry-over devices thereon, indexable denominational reciprocating driveracks, rotative idlers permanently in rnesh with said racks to be driven thereby, a general operator for cycling said drive-racks, while the digit wheels mesh either with' said rach or said idlers for rotations in opposite directions, so that the advance movement of the racks will cause'the digit-wheels either to sod or to subtract, and carry-over mechanism operative to enable any digit-wheel except the highest to cause the rack ot next higher denomination to be advanced a step more than said general operator, to thereby carry over to or borrow from the digit-wheel l driven by said higher rack, said carry-over mechanism including means enabling any digit-wheel at the carry-over operation to eil'ect the recited rack-advance irrespective of whether the digitwheelsareinthepositiontomeshwithsaid *racks or in the position to mesh with said idlers.

16. In a direct-subtraction key-set computing machine. the combination of a group oi' digitwheels having carry-over devices thereon, indexable denominational reciprocating drive-racks, rotative idlers permanently in mesh with said racks to be driven thereby, a general operator i'or cycling said drive-racks, while said digitwheels mesh either with said racks or said idlersv said general operator for carrying over to or borrowing i'rom the digit-wheel driven by said higherrack, said enabling means including provision so as to be operative irrespective oi whether the digit-wheels are in the position to mesh with said racks or in the position to mesh with said idlers.

17. In a computing machine, a plurality o! rotatable register-wheels having carry-over teeth, indexable denominational racks to rotate the wheels predetermined indexed extents, and a general operator to reciprocate said racks. in combination with an adjustable carry-over determinator. a latch to hold said carry-over determinator in ineffective position. means engaged by the tooth of the wheel of next lower denomination to trip said latch and thereby cause said carry-over determinator to be adjusted to ei'iective position, and rack-projecting means movable along with and relatively to said general operator, said rack-projecting means, near the end of the rack-advancing stroke of the general operator. engaging with said eil'ectively positioned carry-over determinator and being thereby operated to drive said rack beyond the range of general-operator movement, for rotating its wheel one extra unit step.

18. In a direct-subtraction key-set computing machine, the combination of a group oi digitwheels having carry-over devices thereon, indexable denominational reciprocating drive-racks, rotative idlers permanently in mesh with said racks to be driven thereby, a general operator i'or cycling said drive-racks, while said digit-wheels mesh either with said racks or said idlers for rotations in opposite directions, so that the advance movement of the racks will cause the digit-wheels either to add or to subtract, and carry-over mechanism including, for each digit-wheel except the highest. a rack-advancer which is individual to the rack of next higher denomination and is driven along with. andis dilvlaceabie relatively to. said general operator. a carry-over demalle! and displaeessaidracbadvancertoadvaneeaaidg whether tno amt-wheels m m tl position to 0 man wltnstla mrs or in tnt posluontomesn with said idlers.

19. In adirect-subtraction key-set machine, the combination of a group. ot digitwheels having carry-over devices thereon. indexracks to bedriven thereby, a general operator tor cycling said drive-racks, while seid digit wheels mesh either with ssld racks or said idlers ier rotations in opposite directions. so that vancemovement of the racks will cause the daltwheeis either to add or to subtract. and

over mechanism including. tor each rack except the lowest. a rack-advancer driven general operator. for carrying Ov!! t9 or borrowing from the digit-wheel driven by laid said enabling means including provision to be operative irrespective of whether the wheels are in the position to mesh with said racks, or inthe position to mesh witheaid idlers.

20. The invention as set forth in claim 18 including an adjustable rack-verthrow-M- ing correlated to said carry-over determinator, so that, when. the latter is respectively in ined tive and eil'ective positions, said atop is positioned to limit any rack-advance which, respectively. does not or does include a carrying step. laid correlation o! said stop and carry-over determinatolproviding for apropriate adiustment o! the n stop under control of solo lower digit-wheel irreptective or the recited diii'erent positions of the a ter.

21. A computing machine having, in combimtion, a plurality oi' digit-wheels. each wheel having a carry-over device, denominational driverscks for sala digit-wheels, dieit-pins for each drive-rack, said pins being settfable for predetermining the distances said racks aie to be advaulted to rotate the amt-wheels. t reciprocatory general operator to co-operate with the set pins for advancing said racks, and carry-over mechanism 'including for each rack. except the lowest, a spring-pressed carry-over determinator latched normally in inoperative position. means enabling the carry-over device for the digit-wheel of next lower denomination to said rack to release said latched carry-over determinator for resultant movement to carry-over-determining position, as said lower digit-Wheel takes a carryover step, and a rack-advancing means driven along with said general operator, said rack-advancing means being also movable relatively to said general operator, to coact with the set digitpin for said rack for advancing said rack beyond the general-operator advance, said carry-over determinator being operative, when released, to act upon said rack-advancing means and advance the latter a step ahead of said general operator as said general operator nears the end of its advance stroke, to thereby advance said rack and its digit-wheel an extra unit of distance for carrying.

22. In a direct-subtraction computing machine, the combination of a plurality of digit- Wheels, indexable denominational wheel-rotating means, a shift of said wheels, from an idle position, in one or another of two substantially perpendicular directions, to different positions to engage said wheel-rotating means, determining forward or backward rotation of the digit-Wheels, a general operator for reciprocating said denominational wheel-rotating means to extents depending on the indexing thereof, a carry-over mechanism, including for each digit-wheel, exceptl the highest, a train extending from said wheel toward the Wheel-rotating means of next higher denomination, said train including a member settable to condition said train preparatory to an ensuing carry-over, means enabling said digit-wheel as it takes a carrying step to set up said member irrespective of the direction of shift and resultant position of said digitwheels, and means co-operable with said general operator and with said carry-over train, to actuate said denominational wheel-rotating means to extents determined partly by the indexing thereof and partly by said carry-over train, the latter being effective when conditioned by said digitwhcel for a carry-over operation to cause said wheel-rotating means of next higher denomination to be advanced a carry-over step beyond the advance vmovement of said general operator.

23. The combination of a plurality of digit- Wheels, reciprocatory denominational driving members for said digit-wheels, a shift of said digit-wheels in one or another of substantially perpendicular directions from a normally disengaged position to two positions determining, respectively, forward or backward rotation of said digit-wheels, indexing means for the driving members, a carry-over train for each digitwheel, except the highest, and extending from said digit-wheel to the driving member of next higher denomination, said train including a member settable to condition said train for a carry-over operation, means enabling said digit- Wheel as it takes a carry-over step to set said member, said means including provision so as to be operative irrespective of the direction of shift and resultant position of said digit-wheels, and means cooperable with said indexing means, said driving members and said carry-over train to cause said driving members to drive said digitwheels forwardly or backwardly, to individual extents determined partly by the indexing and partly by the conditioning of the carry-over train.

24. The combination of a plurality of digitwheels, reciprocatory denominational driving members for said digit-Wheels, a shift of said wheels in one or another of substantially perpendicular directions from a normally disengaged position to two positions determining respectively, forward or backward rotation of said digitwheels, indexing means for the driving members, a general operator co-operable with said indexing means to drive the digit-wheels forwardly or backwardly, to the extents indexed, a carry-over train for each digit-wheel, except the highest, and extending from said digit-wheel to the driving member o f next higher denomination, said train including a member settable to condition said train for a carry-over operation, means enabling said digit-wheel as it takes a carry-over step to set said member, said means including provision so as to be operative irrespective of the direction of shift and resultant position of said digit-wheels, and means co-operative with the carry-over train, when the latter is conditioned for a carry-over operation, to give said higher driving member an additional step of advance and the digit-Wheel driven by said higher driving member, an additional step of forward or backward rotation.

25. A direct-subtraction key-set computing machine including, in combination, a plurality of digit-wheels, key-indexable denominational recprocatory driving racks, idle gears driven by said racks, a general operator for cycling said racks while said digit-wheels mesh either with the racks or with the idle gears, a carry-over train for each digit-wheel, except the highest, and extending therefrom to control the rack of next higher denomination, means operative, irrespective of whether the digit-wheels are positioned to mesh with the racks or with the idle gears, for enabling said digit-wheel as it takes a carry-over step to render the carry-over train effective, and means cri-operative with the effective carry-over train for imparting to said rack of next higher denomination an additional step of advance and to the digit-wheel driven by said rack an additional step of either advance or retraction, dependent upon whether the digit-wheels are meshing with the racks or idle gears.

26. A direct-subtraction key-set computing machine including, in combination, a plurality of digit-wheels, key-indexable denominational driving racks, idle gears meshing with the racks and driven thereby, the digit-wheels meshing with either the racks or with the idle gears, so that the advance of the racks may drive the digitwheels either forwardly or backwardly for addition or subtraction states, and carry-over mechanism including for each digit-wheel, a carryover train extending from said digit-wheel to control the rack of next higher denomination, said train including a portion conditioned according to the state of the digit-wheels to enable said digit-wheel as it takes a carry-over step t operate said train, the remainder of said train being extraneous to said wheels so as to control the next higher rack, said portion and said remainder of said train being relatively arranged so as to co-operate to control said rack irrespective of the state of the digit-wheels, and mens co-operative with said carry-over train for causing an extra step of advance to be imparted to said rack of next higher denomination.

2.7. In a key-set, direct-subtraction computing machine, the combination of a plurality 0f digitwheels, key-indexable reciprocatory denominational racks, idle gears meshing with the racks and driven thereby, the digit-Wheels meshing with either the racks or the idle gears, so that the 

